I live on steep, 50' deep of dirt hillside(granite below that depth). With new development, most trees are gone and replaced with very shallow rooted vegetation such as grass and impervious surfaces. I am concerned about hillside stability. Would like to plant deep rooted shrubs/small trees as certain key areas to help stabilize soil. Need to be deer resistant. Any suggestions? I have a couple of natural break areas in grass areas due to terracing. These would be good places for the deep rooted plants. Limited max height of about 25' due to need to avoid blocking house views. I haven't seen any resources classifying plants by root depth.